Compared with the hustle and bustle of waking life, sleep looks dull and unworkmanlike. Except for in its dreams, a sleeping brain doesn’t misbehave or find a job. It also doesn’t love, scheme, aspire or really do much we would be proud to take credit for. Yet during those quiet hours when our mind is on hold, our brain does the essential labor at the heart of all creative acts. It edits itself. And it may throw out a lot.

In a provocative new theory about the purpose of sleep, neuroscientist Giulio Tononi of the University of Wisconsin–Madison has proposed that slumber, to cement what we have learned, must also spur the brain’s undoing. As the conscious mind settles into sleep, the neural connections that create a scaffold for our knowledge must partially unravel, his theory suggests. Although this nightly dismantling might seem like a curious act of cerebral self-sabotage, it may in fact be a mechanism for enhancing the brain’s capacity to encode and store new information.